blockOn.eb fails in greenlet.throw

Running unit tests on Ubuntu-8.41 python 2.5.2-11, python-codespeak from repository. test_defer.BlockOnTests.test_errback fails, the exception doesn't get appended to events. changing the code of blockOn.eb to look like this, which is code from the docs for greenlet.throw, makes the test pass, which makes me believe that greenlet.throw is messed up

 def eb(failure):
        if greenlet.getcurrent() is current:
            synchronous.append(failure)
        else: # Oh crap, this else is untested!
            #failure.throwExceptionIntoGenerator(current)
            def raiser():
                raise failure.type, failure.value, failure.tb
            g_raiser = greenlet(raiser, parent=current)
            g_raiser.switch()